Arnica sororia

Greene
Ottawa Naturalist 23: 213. 1910.
Common names: Twin arnica
Endemic
Synonyms: Arnica fulgens var. sororia (Greene) G. W. Douglas & Ruyle-Douglas
Treatment appears in FNA Volume 21. Treatment on page 370. Mentioned on page 367.

Plants 15–50 cm. Stems (1 or relatively few) simple or branched. Leaves 3–6 pairs, crowded toward stem bases (axils lacking tufts of brown wool); petiolate (petioles, at least basal, narrowly winged); blades (with 3 or 5, prominent, subparallel veins) oblanceolate to narrowly oblong, 3.5–14.5 × 0.6–2.4 cm, margins usually entire, rarely denticulate, apices obtuse, faces uniformly hairy, stipitate-glandular. Heads 1–5. Involucres hemispheric. Phyllaries 13–20, usually narrowly, sometimes broadly, lanceolate. Ray florets 9–17; corollas yellow-orange. Disc florets: corollas yellow; anthers yellow. Cypselae brown, 3.5–5 mm, densely hirsute, sometimes sparingly glandular as well; pappi white, bristles barbellate. 2n = 38.


Phenology: Flowering May–Jul.
Habitat: Prairies and grasslands to montane conifer forests
Elevation: 500–1500 m

Distribution

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Alta., B.C., Sask., Calif., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.

Discussion

Selected References

None.

Lower Taxa

None.